﻿/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  Latitude/longitude spherical geodesy formulae & scripts (c) Chris Veness 2002-2010            */
/*   - www.movable-type.co.uk/scripts/latlong.html                                                */
/*                                                                                                */
/*  Sample usage:                                                                                 */
/*    var p1 = new LatLon(51.5136, -0.0983);                                                      */
/*    var p2 = new LatLon(51.4778, -0.0015);                                                      */
/*    var dist = p1.distanceTo(p2);          // in km                                             */
/*    var brng = p1.bearingTo(p2);           // in degrees clockwise from north                   */
/*    ... etc                                                                                     */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  Note that minimal error checking is performed in this example code!                           */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */


/**
* Creates a point on the earth's surface at the supplied latitude / longitude
*
* @constructor
* @param {Number} lat: latitude in numeric degrees
* @param {Number} lon: longitude in numeric degrees
* @param {Number} [rad=6371]: radius of earth if different value is required from standard 6,371km
*/
function LatLon(lat, lon, rad) {
    if (typeof(rad) == 'undefined') rad = 6371; // earth's mean radius in km
    // only accept numbers or valid numeric strings
    this._lat = typeof(lat) == 'number' ? lat : typeof(lat) == 'string' && lat.trim() != '' ? +lat : NaN;
    this._lon = typeof(lon) == 'number' ? lon : typeof(lon) == 'string' && lon.trim() != '' ? +lon : NaN;
    this._radius = typeof(rad) == 'number' ? rad : typeof(rad) == 'string' && trim(lon) != '' ? +rad : NaN;
}

/**
* Returns the distance from this point to the supplied point, in km 
* (using Haversine formula)
*
* from: Haversine formula - R. W. Sinnott, "Virtues of the Haversine",
*       Sky and Telescope, vol 68, no 2, 1984
*
* @param   {LatLon} point: Latitude/longitude of destination point
* @param   {Number} [precision=4]: no of significant digits to use for returned value
* @return {Number} Distance in km between this point and destination point
*/
LatLon.prototype.distanceTo = function(point, precision) {
    // default 4 sig figs reflects typical 0.3% accuracy of spherical model
    if (typeof precision == 'undefined') precision = 4;

    var r = this._radius;
    var lat1 = this._lat.toRad(), lon1 = this._lon.toRad();
    var lat2 = point._lat.toRad(), lon2 = point._lon.toRad();
    var dLat = lat2 - lat1;
    var dLon = lon2 - lon1;

    var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
        Math.cos(lat1) * Math.cos(lat2) *
            Math.sin(dLon / 2) * Math.sin(dLon / 2);
    var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
    var d = r * c;
    return d.toPrecisionFixed(precision) * 1; // Fix * 1
};

/**
* Returns the (initial) bearing from this point to the supplied point, in degrees
*   see http://williams.best.vwh.net/avform.htm#Crs
*
* @param   {LatLon} point: Latitude/longitude of destination point
* @return {Number} Initial bearing in degrees from North
*/
LatLon.prototype.bearingTo = function(point) {
    var lat1 = this._lat.toRad(), lat2 = point._lat.toRad();
    var dLon = (point._lon - this._lon).toRad();
    var y = Math.sin(dLon) * Math.cos(lat2);
    var x = Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1) * Math.cos(lat2) * Math.cos(dLon);
    var brng = Math.atan2(y, x);
    return (brng.toDeg() + 360) % 360;
};

/**
* Returns final bearing arriving at supplied destination point from this point; the final bearing 
* will differ from the initial bearing by varying degrees according to distance and latitude
*
* @param   {LatLon} point: Latitude/longitude of destination point
* @return {Number} Final bearing in degrees from North
*/
LatLon.prototype.finalBearingTo = function(point) {
    // get initial bearing from supplied point back to this point...
    var lat1 = point._lat.toRad(), lat2 = this._lat.toRad();
    var dLon = (this._lon - point._lon).toRad();

    var y = Math.sin(dLon) * Math.cos(lat2);
    var x = Math.cos(lat1) * Math.sin(lat2) -
        Math.sin(lat1) * Math.cos(lat2) * Math.cos(dLon);
    var brng = Math.atan2(y, x);

    // ... & reverse it by adding 180°
    return (brng.toDeg() + 180) % 360;
};

/**
* Returns the midpoint between this point and the supplied point.
*   see http://mathforum.org/library/drmath/view/51822.html for derivation
*
* @param   {LatLon} point: Latitude/longitude of destination point
* @return {LatLon} Midpoint between this point and the supplied point
*/
LatLon.prototype.midpointTo = function(point) {
    var lat1 = this._lat.toRad(), lon1 = this._lon.toRad();
    var lat2 = point._lat.toRad();
    var dLon = (point._lon - this._lon).toRad();

    var bx = Math.cos(lat2) * Math.cos(dLon);
    var by = Math.cos(lat2) * Math.sin(dLon);

    var lat3 = Math.atan2(Math.sin(lat1) + Math.sin(lat2), 
        Math.sqrt((Math.cos(lat1) + bx) * (Math.cos(lat1) + bx) + by * by));
    var lon3 = lon1 + Math.atan2(by, Math.cos(lat1) + bx);

    return new LatLon(lat3.toDeg(), lon3.toDeg());
};

/**
* Returns the destination point from this point having travelled the given distance (in km) on the 
* given initial bearing (bearing may vary before destination is reached)
*
*   see http://williams.best.vwh.net/avform.htm#LL
*
* @param   {Number} brng: Initial bearing in degrees
* @param   {Number} dist: Distance in km
* @return {LatLon} Destination point
*/
LatLon.prototype.destinationPoint = function(brng, dist) {
    dist = typeof(dist) == 'number' ? dist : typeof(dist) == 'string' && dist.trim() != '' ? +dist : NaN;
    dist = dist / this._radius; // convert dist to angular distance in radians
    brng = brng.toRad(); // 
    var lat1 = this._lat.toRad(), lon1 = this._lon.toRad();

    var lat2 = Math.asin(Math.sin(lat1) * Math.cos(dist) +
        Math.cos(lat1) * Math.sin(dist) * Math.cos(brng));
    var lon2 = lon1 + Math.atan2(Math.sin(brng) * Math.sin(dist) * Math.cos(lat1),
        Math.cos(dist) - Math.sin(lat1) * Math.sin(lat2));
    lon2 = (lon2 + 3 * Math.PI) % (2 * Math.PI) - Math.PI; // normalise to -180...+180

    return new LatLon(lat2.toDeg(), lon2.toDeg());
};

/**
* Returns the point of intersection of two paths defined by point and bearing
*
*   see http://williams.best.vwh.net/avform.htm#Intersection
*
* @param   {LatLon} p1: First point
* @param   {Number} brng1: Initial bearing from first point
* @param   {LatLon} p2: Second point
* @param   {Number} brng2: Initial bearing from second point
* @return {LatLon} Destination point (null if no unique intersection defined)
*/
LatLon.intersection = function (p1, brng1, p2, brng2) {
    brng1 = typeof brng1 == 'number' ? brng1 : typeof brng1 == 'string' && trim(brng1) != '' ? +brng1 : NaN;
    brng2 = typeof brng2 == 'number' ? brng2 : typeof brng2 == 'string' && trim(brng2) != '' ? +brng2 : NaN;
    var lat1 = p1._lat.toRad(), lon1 = p1._lon.toRad();
    var lat2 = p2._lat.toRad(), lon2 = p2._lon.toRad();
    var brng13 = brng1.toRad(), brng23 = brng2.toRad();
    var dLat = lat2 - lat1, dLon = lon2 - lon1;

    var dist12 = 2 * Math.asin(Math.sqrt(Math.sin(dLat / 2) * Math.sin(dLat / 2) +
        Math.cos(lat1) * Math.cos(lat2) * Math.sin(dLon / 2) * Math.sin(dLon / 2)));
    if (dist12 == 0) return null;

    // initial/final bearings between points
    var brngA = Math.acos((Math.sin(lat2) - Math.sin(lat1) * Math.cos(dist12)) /
        (Math.sin(dist12) * Math.cos(lat1)));
    if (isNaN(brngA)) brngA = 0; // protect against rounding
    var brngB = Math.acos((Math.sin(lat1) - Math.sin(lat2) * Math.cos(dist12)) /
        (Math.sin(dist12) * Math.cos(lat2)));

    var brng12, brng21;
    if (Math.sin(lon2 - lon1) > 0) {
        brng12 = brngA;
        brng21 = 2 * Math.PI - brngB;
    } else {
        brng12 = 2 * Math.PI - brngA;
        brng21 = brngB;
    }

    var alpha1 = (brng13 - brng12 + Math.PI) % (2 * Math.PI) - Math.PI; // angle 2-1-3
    var alpha2 = (brng21 - brng23 + Math.PI) % (2 * Math.PI) - Math.PI; // angle 1-2-3

    if (Math.sin(alpha1) == 0 && Math.sin(alpha2) == 0) return null; // infinite intersections
    if (Math.sin(alpha1) * Math.sin(alpha2) < 0) return null; // ambiguous intersection

    //alpha1 = Math.abs(alpha1);
    //alpha2 = Math.abs(alpha2);
    // ... Ed Williams takes abs of alpha1/alpha2, but seems to break calculation?

    var alpha3 = Math.acos(-Math.cos(alpha1) * Math.cos(alpha2) +
        Math.sin(alpha1) * Math.sin(alpha2) * Math.cos(dist12));
    var dist13 = Math.atan2(Math.sin(dist12) * Math.sin(alpha1) * Math.sin(alpha2),
        Math.cos(alpha2) + Math.cos(alpha1) * Math.cos(alpha3));
    var lat3 = Math.asin(Math.sin(lat1) * Math.cos(dist13) +
        Math.cos(lat1) * Math.sin(dist13) * Math.cos(brng13));
    var dLon13 = Math.atan2(Math.sin(brng13) * Math.sin(dist13) * Math.cos(lat1),
        Math.cos(dist13) - Math.sin(lat1) * Math.sin(lat3));
    var lon3 = lon1 + dLon13;
    lon3 = (lon3 + Math.PI) % (2 * Math.PI) - Math.PI; // normalise to -180..180º

    return new LatLon(lat3.toDeg(), lon3.toDeg());
};

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

/**
* Returns the distance from this point to the supplied point, in km, travelling along a rhumb line
*
*   see http://williams.best.vwh.net/avform.htm#Rhumb
*
* @param   {LatLon} point: Latitude/longitude of destination point
* @return {Number} Distance in km between this point and destination point
*/
LatLon.prototype.rhumbDistanceTo = function(point) {
    var r = this._radius;
    var lat1 = this._lat.toRad(), lat2 = point._lat.toRad();
    var dLat = (point._lat - this._lat).toRad();
    var dLon = Math.abs(point._lon - this._lon).toRad();

    var dPhi = Math.log(Math.tan(lat2 / 2 + Math.PI / 4) / Math.tan(lat1 / 2 + Math.PI / 4));
    var q = (!isNaN(dLat / dPhi)) ? dLat / dPhi : Math.cos(lat1); // E-W line gives dPhi=0
    // if dLon over 180° take shorter rhumb across 180° meridian:
    if (dLon > Math.PI) dLon = 2 * Math.PI - dLon;
    var dist = Math.sqrt(dLat * dLat + q * q * dLon * dLon) * r;

    // FIX: *1 to cast to number
    return dist.toPrecisionFixed(4) * 1; // 4 sig figs reflects typical 0.3% accuracy of spherical model
};

/**
* Returns the bearing from this point to the supplied point along a rhumb line, in degrees
*
* @param   {LatLon} point: Latitude/longitude of destination point
* @return {Number} Bearing in degrees from North
*/
LatLon.prototype.rhumbBearingTo = function(point) {
    var lat1 = this._lat.toRad(), lat2 = point._lat.toRad();
    var dLon = (point._lon - this._lon).toRad();

    var dPhi = Math.log(Math.tan(lat2 / 2 + Math.PI / 4) / Math.tan(lat1 / 2 + Math.PI / 4));
    if (Math.abs(dLon) > Math.PI) dLon = dLon > 0 ? -(2 * Math.PI - dLon) : (2 * Math.PI + dLon);
    var brng = Math.atan2(dLon, dPhi);
    return (brng.toDeg() + 360) % 360;
};

/**
* Returns the destination point from this point having travelled the given distance (in km) on the 
* given bearing along a rhumb line
*
* @param  {Number} brng: Bearing in degrees from North
* @param  {Number} dist: Distance in km
* @return {LatLon} Destination point
*/
LatLon.prototype.rhumbDestinationPoint = function(brng, dist) {
    var r = this._radius;
    var d = parseFloat(dist) / r; // d = angular distance covered on earth's surface
    var lat1 = this._lat.toRad(), lon1 = this._lon.toRad();
    brng = brng.toRad();

    var lat2 = lat1 + d * Math.cos(brng);
    var dLat = lat2 - lat1;
    var dPhi = Math.log(Math.tan(lat2 / 2 + Math.PI / 4) / Math.tan(lat1 / 2 + Math.PI / 4));
    var q = (!isNaN(dLat / dPhi)) ? dLat / dPhi : Math.cos(lat1); // E-W line gives dPhi=0
    var dLon = d * Math.sin(brng) / q;
    // check for some daft bugger going past the pole
    if (Math.abs(lat2) > Math.PI / 2) lat2 = lat2 > 0 ? Math.PI - lat2 : -(Math.PI - lat2);
    var lon2 = (lon1 + dLon + 3 * Math.PI) % (2 * Math.PI) - Math.PI;
    return new LatLon(lat2.toDeg(), lon2.toDeg());
};

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

/**
* Returns the latitude of this point; signed numeric degrees if no format, otherwise format & dp 
* as per Geo.toLat()
*
* @param   {String} [format]: Return value as 'd', 'dm', 'dms'
* @param   {Number} [dp=0|2|4]: No of decimal places to display
* @return {Number|String} Numeric degrees if no format specified, otherwise deg/min/sec
*
* @requires Geo
*/
LatLon.prototype.lat = function(format, dp) {
    if (typeof format == 'undefined') return this._lat;

    return Geo.toLat(this._lat, format, dp);
};

/**
* Returns the longitude of this point; signed numeric degrees if no format, otherwise format & dp 
* as per Geo.toLon()
*
* @param   {String} [format]: Return value as 'd', 'dm', 'dms'
* @param   {Number} [dp=0|2|4]: No of decimal places to display
* @return {Number|String} Numeric degrees if no format specified, otherwise deg/min/sec
*
* @requires Geo
*/
LatLon.prototype.lon = function(format, dp) {
    if (typeof format == 'undefined') return this._lon;
    return Geo.toLon(this._lon, format, dp);
};

/**
* Returns a string representation of this point; format and dp as per lat()/lon()
*
* @param   {String} [format]: Return value as 'd', 'dm', 'dms'
* @param   {Number} [dp=0|2|4]: No of decimal places to display
* @return {String} Comma-separated latitude/longitude
*
* @requires Geo
*/
LatLon.prototype.toString = function(format, dp) {
    if (typeof format == 'undefined') format = 'dms';
    if (isNaN(this._lat) || isNaN(this._lon)) return '-,-';
    return Geo.toLat(this._lat, format, dp) + ', ' + Geo.toLon(this._lon, format, dp);
};

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

// ---- extend Number object with methods for converting degrees/radians

/** Converts numeric degrees to radians */
if (typeof(Number.prototype.toRad) === "undefined") {
    Number.prototype.toRad = function() {
        return this * Math.PI / 180;
    };
}
;

/** Converts radians to numeric (signed) degrees */
if (typeof(Number.prototype.toDeg) === "undefined") {
    Number.prototype.toDeg = function() {
        return this * 180 / Math.PI;
    };
}
;

/** 
* Formats the significant digits of a number, using only fixed-point notation (no exponential)
* 
* @param   {Number} precision: Number of significant digits to appear in the returned string
* @return {String} A string representation of number which contains precision significant digits
*/
if (typeof(Number.prototype.toPrecisionFixed) === "undefined") {
    Number.prototype.toPrecisionFixed = function (precision) {
        if (isNaN(this)) return 'NaN';
        var numb = this < 0 ? -this : this; // can't take log of -ve number...
        var sign = this < 0 ? '-' : '';

        if (numb == 0) {
            n = '0.';
            while (precision--) n += '0';
            return n;
        }
        ; // can't take log of zero

        var scale = Math.ceil(Math.log(numb) * Math.LOG10E); // no of digits before decimal
        var n = String(Math.round(numb * Math.pow(10, precision - scale)));
        if (scale > 0) { // add trailing zeros & insert decimal as required
            var l = scale - n.length;
            while (l-- > 0) n = n + '0';
            if (scale < n.length) n = n.slice(0, scale) + '.' + n.slice(scale);
        } else { // prefix decimal and leading zeros if required
            while (scale++ < 0) n = '0' + n;
            n = '0.' + n;
        }
        return sign + n;
    };
}
;

/** Trims whitespace from string (q.v. blog.stevenlevithan.com/archives/faster-trim-javascript) */
if (typeof(String.prototype.trim) === "undefined") {
    String.prototype.trim = function() {
        return String(this).replace( /^\s\s*/ , '').replace( /\s\s*$/ , '');
    };
};

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  Geodesy representation conversion functions (c) Chris Veness 2002-2010                        */
/*   - www.movable-type.co.uk/scripts/latlong.html                                                */
/*                                                                                                */
/*  Sample usage:                                                                                 */
/*    var lat = Geo.parseDMS('51° 28′ 40.12″ N');                                                 */
/*    var lon = Geo.parseDMS('000° 00′ 05.31″ W');                                                */
/*    var p1 = new LatLon(lat, lon);                                                              */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

var Geo = { };
// Geo namespace, representing static class

/**
* Parses string representing degrees/minutes/seconds into numeric degrees
*
* This is very flexible on formats, allowing signed decimal degrees, or deg-min-sec optionally
* suffixed by compass direction (NSEW). A variety of separators are accepted (eg 3º 37' 09"W) 
* or fixed-width format without separators (eg 0033709W). Seconds and minutes may be omitted. 
* (Note minimal validation is done).
*
* @param   {String|Number} dmsStr: Degrees or deg/min/sec in variety of formats
* @return {Number} Degrees as decimal number
* @throws  {TypeError} dmsStr is an object, perhaps DOM object without .value?
*/
Geo.parseDMS = function(dmsStr) {
    // if (typeof deg == 'object') throw new TypeError('Geo.parseDMS - dmsStr is [DOM?] object');

    // check for signed decimal degrees without NSEW, if so return it directly
    if (typeof dmsStr === 'number' && isFinite(dmsStr)) return Number(dmsStr);

    // strip off any sign or compass dir'n & split out separate d/m/s
    var dms = String(dmsStr).trim().replace( /^-/ , '').replace( /[NSEW]$/i , '').split( /[^0-9.,]+/ );
    if (dms[dms.length - 1] == '') dms.splice(dms.length - 1); // from trailing symbol

    if (dms == '') return NaN;

    // and convert to decimal degrees...
    var deg;
    switch (dms.length) {
    case 3:
// interpret 3-part result as d/m/s
        deg = dms[0] / 1 + dms[1] / 60 + dms[2] / 3600;
        break;
    case 2:
// interpret 2-part result as d/m
        deg = dms[0] / 1 + dms[1] / 60;
        break;
    case 1:
// just d (possibly decimal) or non-separated dddmmss
        deg = dms[0];
            // check for fixed-width unseparated format eg 0033709W
        if ( /[NS]/i .test(dmsStr)) deg = '0' + deg; // - normalise N/S to 3-digit degrees
        if ( /[0-9]{7}/ .test(deg)) deg = deg.slice(0, 3) / 1 + deg.slice(3, 5) / 60 + deg.slice(5) / 3600;
        break;
    default:
        return NaN;
    }
    if ( /^-|[WS]$/i .test(dmsStr.trim())) deg = -deg; // take '-', west and south as -ve
    return Number(deg);
};

/**
* Convert decimal degrees to deg/min/sec format
*  - degree, prime, double-prime symbols are added, but sign is discarded, though no compass
*    direction is added
*
* @private
* @param   {Number} deg: Degrees
* @param   {String} [format=dms]: Return value as 'd', 'dm', 'dms'
* @param   {Number} [dp=0|2|4]: No of decimal places to use - default 0 for dms, 2 for dm, 4 for d
* @return {String} deg formatted as deg/min/secs according to specified format
* @throws  {TypeError} deg is an object, perhaps DOM object without .value?
*/
Geo.toDMS = function (deg, format, dp) {
    if (typeof deg == 'object') throw new TypeError('Geo.toDMS - deg is [DOM?] object');
    if (isNaN(deg)) return 'NaN'; // give up here if we can't make a number from deg

    // default values
    if (typeof format == 'undefined') format = 'dms';
    if (typeof dp == 'undefined') {
        switch (format) {
            case 'd':
                dp = 4;
                break;
            case 'dm':
                dp = 2;
                break;
            case 'dms':
                dp = 0;
                break;
            default:
                format = 'dms';
                dp = 0;
                // be forgiving on invalid format
        }
    }

    deg = Math.abs(deg); // (unsigned result ready for appending compass dir'n)

    var d;
    var m;
    var dms = 0;
    switch (format) {
        case 'd':
            d = deg.toFixed(dp); // round degrees
            if (d < 100) d = '0' + d; // pad with leading zeros
            if (d < 10) d = '0' + d;
            dms = d + '\u00B0'; // add º symbol
            break;
        case 'dm':
            var min = (deg * 60).toFixed(dp); // convert degrees to minutes & round
            d = Math.floor(min / 60); // get component deg/min
            m = (min % 60).toFixed(dp); // pad with trailing zeros
            if (d < 100) d = '0' + d; // pad with leading zeros
            if (d < 10) d = '0' + d;
            if (m < 10) m = '0' + m;
            dms = d + '\u00B0' + m + '\u2032'; // add º, ' symbols
            break;
        case 'dms':
            var sec = (deg * 3600).toFixed(dp); // convert degrees to seconds & round
            d = Math.floor(sec / 3600); // get component deg/min/sec
            m = Math.floor(sec / 60) % 60;
            var s = (sec % 60).toFixed(dp); // pad with trailing zeros
            if (d < 100) d = '0' + d; // pad with leading zeros
            if (d < 10) d = '0' + d;
            if (m < 10) m = '0' + m;
            if (s < 10) s = '0' + s;
            dms = d + '\u00B0' + m + '\u2032' + s + '\u2033'; // add º, ', " symbols
            break;
    }

    return dms;
};

/**
* Convert numeric degrees to deg/min/sec latitude (suffixed with N/S)
*
* @param   {Number} deg: Degrees
* @param   {String} [format=dms]: Return value as 'd', 'dm', 'dms'
* @param   {Number} [dp=0|2|4]: No of decimal places to use - default 0 for dms, 2 for dm, 4 for d
* @return {String} Deg/min/seconds
*/
Geo.toLat = function(deg, format, dp) {
    var lat = Geo.toDMS(deg, format, dp);
    return lat == '' ? '' : lat.slice(1) + (deg < 0 ? 'S' : 'N'); // knock off initial '0' for lat!
};

/**
* Convert numeric degrees to deg/min/sec longitude (suffixed with E/W)
*
* @param   {Number} deg: Degrees
* @param   {String} [format=dms]: Return value as 'd', 'dm', 'dms'
* @param   {Number} [dp=0|2|4]: No of decimal places to use - default 0 for dms, 2 for dm, 4 for d
* @return {String} Deg/min/seconds
*/
Geo.toLon = function(deg, format, dp) {
    var lon = Geo.toDMS(deg, format, dp);
    return lon == '' ? '' : lon + (deg < 0 ? 'W' : 'E');
};

/**
* Convert numeric degrees to deg/min/sec as a bearing (0º..360º)
*
* @param   {Number} deg: Degrees
* @param   {String} [format=dms]: Return value as 'd', 'dm', 'dms'
* @param   {Number} [dp=0|2|4]: No of decimal places to use - default 0 for dms, 2 for dm, 4 for d
* @return {String} Deg/min/seconds
*/
Geo.toBrng = function(deg, format, dp) {
    deg = (Number(deg) + 360) % 360; // normalise -ve values to 180º..360º
    var brng = Geo.toDMS(deg, format, dp);
    return brng.replace('360', '0'); // just in case rounding took us up to 360º!
};